1. Field of the Invention
The present invention relates to a method of and an apparatus for producing a semiconductor device. More particularly, the present invention is concerned with a method of dividing a semiconductor wafer into dice and also with an apparatus for carrying out this method.
2. Description of the Related Art
FIGS. 1A to 1D are schematic illustrations of successive steps of a conventional method of producing a semiconductor device. More specifically, FIG 1A shows a dicing step, FIGS. 1B and 1C show a breaking step and FIG. 1D shows an expanding step. Referring first to the dicing step shown in FIG. 1A, cut lines defining dice are scribed in a wafer 2 fixed on a wafer vacuum table of a dicing apparatus by cutting with a blade 3 to a depth which is about 1/2 the thickness of the wafer 1. After the scribing of the cut lines, the wafer 1 is demounted from the wafer vacuum table 2 and an expandable sheet 4 is adhered to the back side of the wafer 1. In the breaking method shown in FIGS. 1B and 1C, the wafer 1 is divided into dice. More specifically, in the method shown in FIG. 1B, the wafer 1 is placed upside down on a break table 5, and a rotatable break roller is pressed onto the wafer 1 so as to generate cracks along the cut lines, thereby to divide the wafer into dice. On the other hand, in the breaking method shown in FIG 1C, the wafer is placed on a break table 7 such that the scribed side of the wafer 1 is directed upward, and a thin plate 8 capable of being curved along the curvature of the break table 7 is pressed onto the wafer 1 so as to deform the wafer 1 by utilizing the curvature of the break table 7, so that the wafer 1 is cracked along the cut lines and divided into dice. After the breakage of the wafer, the expandable sheet 4 is stretched as shown in FIG. 1D so that the gaps between adjacent dice are enlarged to values greater than the width W.sub.1 of the bevel 1a formed by the breakage, and is fixed by means of an expansion ring 9 in this state. The wafer 1, now assuming a state shown in FIG. 1D, is delivered to a subsequent die bonding step (not shown). Successive lots of wafers, each having a cassette containing about 20 sheets of the wafer, are supplied to the production line.
The described known method of producing semiconductor devices suffers from the following problems.
(a) In view of a risk of the wafer being undesirably cracked during the conveying step after the dicing, it is not allowed to fully or semi-fully cut the wafer, and it can only be cut to half depth. Consequently sometimes the wafer fails to break at a local portion of the wafer. PA0 (2) The breakage is effected by applying pressure to the dice surface, as shown in FIG. 1B or FIG. 1C, so that the dice tend to be damaged, reducing the yield and the quality of the product. PA0 (c) The bevel width is inevitably small due to the fact that the wafer is cut only to half the thickness thereof, so that the expanding step for increasing the dice interval is essentially required. PA0 (d) Conventionally used expansion rings are becoming unusable as a result of the current trend for larger wafers. PA0 (e) Quality of the products undesirably fluctuate due to the employment of manual labor. PA0 (f) Each step is executed on the lot basis so that the efficiency of the work is impaired because the successive steps are conducted independently. Consequently, a long production time is required.